1. Field of the Invention
This invention relates to a material which inhibits generation of electrostatic charges on an outer surface of a plastic film and which is effective in various fields plagued with electrostatic charges, such as the fields of packaging materials, information recording materials, construction materials, printing materials or electronic materials.
2. Description of the Prior Art
Plastic films or laminated products thereof, employed in a variety of technological fields, suffer from a drawback that electrostatic charges are induced on the films by contact or separation due to the dielectric properties of the plastics themselves. If electrostatic charges are induced on the plastic films or laminated products thereof, fine dust or dirt becomes affixed to the film surface, such that the films or laminated products are not usable as packaging material for food or pharmaceuticals. Besides, film feed or discharge characteristics at the time of printing on the plastic film are also deteriorated.
As an antistatic method for plastic film and laminated film, there have been proposed a method of neutralizing the charges by ionized air and a method consisting in mixing or coating an antistatic agent on the film resin. However, the neutralization method is in need of a dedicated device, while its effect is not durable. On the other hand, the method of mixing or coating the antistatic agent into or on the film resin leads to many hindrances because of the presence of the antistatic agent, foreign material to the film base material on the film surface. For example, if the composite film is used as a packaging material for food or pharmaceuticals, problems are raised in connection with toxicity of the antistatic agent, contamination of the food or pharmaceuticals and poor printability. Although attempts have been made for bonding a film comprising such an anti-static agent mixed into or coated on the film resin to another film, there has not been presented a method which fully obviates the above-mentioned prior-art problems.
If such a film is devised whose outer surface is the base film itself, and which exhibits electrostatic charge proof properties, this film represents an ideal material for the subsequent production process and practical application.